Carotenoids can be divided into two classes: —carotenes (polyene hydrocarbons) such as beta-carotene and lycopene, and xanthophylls (oxygenated carotenoids) such as lutein and astaxanthin. These carotenoids are moderately soluble in oil and are insoluble in water, these polyethers are important pigments for food, feed and pharmaceutical industries.
As well as being used for pigments some carotenoids have nutritional value, e.g. beta carotene is a vitamin A precursor and astaxanthin has provitamin A activity in salmon.
Carotenoids are very susceptible to oxidation and heat and will react with oxygen in the air to render them inactive and colourless.
A number of workers have prepared formulations of carotenoids for therapeutic use including the work reported in the documents discussed below. However a reference herein to a patent document or other material which is mentioned as prior art is not to be taken as an admission that that document or material was published or known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.
U.S. Pat. No. 5,460,823 (Jansen et al) relates to a process of preparing microparticles of carotenoids in which solids are milled in an aqueous medium in the presence of a hydrocolloid. The mixture is spray dried to form microparticles of maximum particle size of about 10 microns.
U.S. Pat. No. 5,811,609 (Vilstrup et al) likewise prepares particles by milling carotenoids in aqueous medium to form a suspension in the presence of a hydrocolloid. The suspension is heated to cause melting of the carotenoid which is spray dried to form a powder.
U.S. Pat. No. 6,639,113 (Runge et al) describes the preparation of powdered oxygenated carotenoids such as astascanthin which are formed by dissolving the composition of the oxygenated carotenoid in a solvent at 50° C. to 240° C. which is mixed with a protecting colloid and set before conversion to a powder by spray drying or the like methods. Chimia 21,329 (1967), (see also DE Application No. 12 11 911 and DE Publication No. 25 34 091 disclose methods of dissolving the active compound in a chlorinated organic solvent, emulsifying the solution in a gelatine/sucrose solution and extracting the solvent from the emulsion causing the active compound to crystallize in microcrystalline form. A disadvantage of this method is that it is technically impossible to remove the organic solvent completely and the solvent is a potential hazard during the process and as residues in the final product.
U.S. Pat. No. 5,827,539 (Gellenback at al) prepares a dry carotenoid powder by grinding in an oil to provide particles of about 0.5 microns which are dispersed in an aqueous encapsulating media. Emulsification and drying need to be controlled to avoid the formation of sticky agglomerates of poor stability.
U.S. Pat. No. 6,132,790 (Schlipalius) describes a carotenoid in an oil solvent which is dispersed in an aqueous phase in the presence of an emulsifier to provide fine droplets of oil phase.
U.S. Pat. No. 5,773,026 (Schlipalius) describes use of a natural carotenoids oil composition in a non-toxic water dispersible therapeutic formulation suitable for injection or intravenous use by humans or animals.
U.S. Pat. No. 6,428,816 (Schlipalius et al) describes treatment of melanoma or melanomas by injection of a water insoluble carotenoid component and a mixture of a water dispersible component.
U.S. Pat. No. 5,780,056 (Akamatsu et al) describes natural carotenoid formulated as capsules having a multi core structure provided by heating the carotenoid to 120° C. in an oil and cooling to 70° C. before forming a water in oil emulsion and inverting the phases and encapsulating the resulting oil-in-water emulsion as microfine oil particles.
Naturally sourced oils containing carotenoids such as palm oil, carrot oil etc contain a mixture of carotenoids e.g. alpha carotene, beta-carotene, gamma carotene, lycopene in solubilised form and particulate form. When the oils are refined, these carotenoids are lost or degraded and therefore have a low level of bioavailability.
There is a need for a stable carotenoid composition of high biological activity.